In Ostwald's process for the manufacture of nitric
acid the catalyst used is

Options

A. Finely divided iron
B. Vanadium pentoxide
C. Platinised asbestos
D. Molybdenum

Answer

**Step-by-Step Text Solution:**

1. **Understanding Ostwald's Process**: Ostwald's process is a method for producing nitric acid (HNO3) from ammonia (NH3). It involves several steps and requires a catalyst to speed up the reactions.

2. **Identifying the Reactants**: The primary reactants in Ostwald's process are ammonia (NH3) and oxygen (O2). The first reaction involves these two substances.

3. **First Reaction**: The first reaction can be written as:
\[ 4 \text{NH}_3 (g) + 5 \text{O}_2 (g) \rightarrow 4 \text{NO} (g) + 6 \text{H}_2\text{O} (g) \]
Here, ammonia reacts with oxygen to produce nitric oxide (NO) and water (H2O).

4. **Second Reaction**: The nitric oxide produced then reacts with more oxygen to form nitrogen dioxide (NO2):
\[ 2 \text{NO} (g) + \text{O}_2 (g) \rightarrow 2 \text{NO}_2 (g) \]

5. **Third Reaction**: The nitrogen dioxide then reacts with water to produce nitric acid:
\[ 4 \text{NO}_2 (g) + 2 \text{H}_2\text{O} (g) \rightarrow 4 \text{HNO}_3 (aq) \]

6. **Identifying the Catalyst**: In Ostwald's process, the catalyst used is platinized asbestos. This catalyst helps to accelerate the reactions without being consumed in the process.

7. **Conclusion**: Therefore, the catalyst used in Ostwald's process for the manufacture of nitric acid is **platinized asbestos**.

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